DESCRIPTION; This will be held in Portland, Oregon in the Summer of 1998. The objectives are: (1) to assemble speakers and participants consisting of basic scientists and clinicians from diverse backgrounds and interests, including stem cell biology, gene therapy of hematopoietic stem cells, genetic diseases, immunology, transplantation biology, obstetrics, fetal surgery, neonatology and medical ethicists; (2) to present and discuss the latest finding on in utero hematopoietic stem cell transplantation and gene therapy; (3) to identify and fully discuss controversial issues related to clinical application of this technology; (4) to foster interdisciplinary collaborations; and (5) to identify areas in need of additional basic and preclinical research as a prerequisite for continued clinical progress. Major topics to be discussed include (a) stem cell biology and transplantation; (b) stem cell gene therapy; (c) animal studies of in utero stem cell transplantation; (d) GVHD and induction of tolerance; (e) in utero gene transfer in animal models; (f) clinical experiences with gene therapy and in utero stem cell transplantation; and (g) medical ethics of in utero stem cell transplantation and gene therapy.